Some printers may be used to produce multiple copies of photo quality images. To insure the color consistency between each copy of the image, the printer may be calibrated between print runs, or continually during a print run. A printer is typically color calibrated by printing a target with patches using known color values. The target is scanned and the scanned color values are compared to the known color values. The difference between the scanned color values and the known color values are used to adjust the printer to minimize the difference between the color of the printed patches and the expected or known color.
Problems can occur when scanning the color patches on the printed target. The type of scanner typically used to scan the color patches on the target may be sensitive to the distance between the scanner and the target, as well as the angle between the surface of the target and the scanner. The distance between the scanner and the target and the angle between the target's surface and the scanner may vary due to a number of factors. For example, as the target is moved past the scanner, bubbles, wrinkles or creases may form in the target. The bubbles and/or creases may change the distance and angle between the target's surface and the scanner. In addition, the target may not be held down uniformly across the scanning area. These variations in target location and angle can cause inaccuracies in the measurement of the color patches on the target. Inaccuracies in the measured patches will cause inaccuracies in the color calibration of the printer.